Final answer:
To find the time it will take for the car to stop when decelerating at a constant rate from 40 m/s with an acceleration of -5 m/s2, we use the kinematic equation. After setting the final velocity to 0 m/s and solving for time, we determine that it takes the car 8 seconds to come to a stop.
Step-by-step explanation:
To calculate the time it takes for a car slowing down at a constant rate from 40 m/s to come to a stop with an acceleration of -5 m/s2, we can use the kinematic equation that relates initial velocity, final velocity, acceleration, and time:
final velocity = initial velocity + (acceleration × time)
We know the final velocity is 0 m/s (since the car comes to a rest), the initial velocity is 40 m/s, and the acceleration is -5 m/s2 (negative because the car is decelerating). Using this information, we set up the equation as follows:
0 m/s = 40 m/s + (-5 m/s2 × time)
By solving for time, we get:
time = (0 m/s - 40 m/s) / (-5 m/s2)
time = 8 seconds
Therefore, it will take the car 8 seconds to come to a stop.